In the practice of prosthetic dentistry when preparing dentures the dentist typically prepares an initial trial plate consisting of wax or other similar material in which the prosthetic teeth are set in their proper positions. When this trial denture has been made and fitted to the mouth of the patient and found satisfactory with respect to aesthetics, fit and articulation, it is then subjected to a process in which a permanent plastic material is essentially substituted for the wax. In this process of producing a denture, the trial dentures are attached by wax to a cast which is then placed in one half of a container known as a flask. The two halves of the flask are then secured and plaster is poured into the flask covering the trial denture. When this investment has hardened, the flask containing the investment is heated until the wax is softened enough to be removed. The halves of the investment thereby form a cavity mold already containing the prosthetic teeth in proper position in which a permanent plastic material such as a resin of methyl methacrylate is packed. The halves of the investment are then fitted together and the halves of the flask containing them are forced together in a press. As the two halves of the flask are forced together, excessive plastic material will ooze out between the two opposite faces. Following curing, the flask is removed from the press and excessive plastic material is removed.
Typically the dental flasks which are used in the manufacture or formation of dentures consist of a three part unit having a base, a body and a lid which fit together to comprise an easily removable container for denture molding materials. Various dental flasks together with improvements and variations of these flasks are described, for example, in U.S. Pat. No. 5,338,192 to Weber.
In the actual formation of the dentures, it is necessary that a considerable amount of pressure be applied to the dental flask containing the mold and dental material. This pressure is applied by means of the press into which one or more of the dental flasks are placed. Both the flask and the press must be heavily constructed, typically of bronze. It is necessary that substantial pressure be applied to the flasks which are placed within the press it in order to assure proper alignment of the mold and to force out any air pockets that might result in unwanted porosity. This is achieved by screwing down a plate which compresses onto the flask or flasks. The flask, so compressed is then submerged in hot water for curing.
Heretofore, compression and removal of the dental flasks from their frames has been accomplished by means of a simple hex key and pin. This arrangement has not permitted the dental flask and frame to remain stationary while the press is either compressed or released in order to remove the flasks. Consequently, it has frequently been necessary for more than one technician to actually take part in this procedure. Furthermore, because it requires considerable strength, effort and dexterity to apply the pressure in this way, maximum pressure it not always achieved. It would accordingly be desirable to provide a frame which would firmly and securely hold the dental press both while compression of the dental flasks within the press is taking place and during the procedure whereby the frame is released for removal of the dental flasks. It would especially be desirable if such a frame were to permit the operation of the press in the aforementioned manner by a single technician using only one hand. A further desirable feature would be to provide more complete compression of the frame and dental flasks to thereby eliminate voids or porosity in the final dental prosthesis. These and other desirable objectives are achieved by the present invention.